Wood joint



June 1, 1937. Tmpp 1 2,082,431

w oon JOINT Filed April 4, 1935 IVENTOR,

Elwood I Tripp, I BYv E? ATTORNEY.

Patented June 1, 1937 v UNITED STATES PATENT OFFICE woon JOINT Washington Application April 4, 1935, Serial No. 14,620

4 Claims.

This invention relates to wood joints, to box ends and the like comprising such joints, and to methods for the formation thereof.

An object ofthe invention is the provision of a wood joint whereby two pieces of wood will be effectively held together and which may be readily formed.

Anotherobject is to provide a simple and effective method of providing such a joint.

Another object is to provide acomposite box end and the like wherein the parts are securely held together and which may be formed with especial ease. I

Still another object is to provide an improved method for the formation of box ends and like articles.

Other objects of the invention willin part be obvious and will in part appear hereinafter.

The invention accordingly comprises the sev-" eral steps and the relation and order of one or more of such steps with respect to each of the others, and the article possessing. the features, properties, and the relation of'elements, which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 is a perspective View of a double-end blank for box ends embodying the invention;

Fig. 2 is an end view of a box end formed therefrom;

Fig. 3 is an enlarged view illustrating a form of wood joint embodying the invention and com prised by the various forms of construction examplified;

Fig. 4 shows one of the pieces of the wood joint of Fig. 3 ready for joining; i

Fig. 5 shows the other piece of the wood joint of Fig. 3 ready for joining;

Fig. 6 shows a manner in which a wood joint such as contemplated by the invention may be utilized in flooring;

Fig. 7 shows a manner in which a wood'joint such as contemplated by the invention may be utilized in furniture framework; and Fig. 8 shows the manner in which a wood joint such as contemplated by the invention may be utilized in doors.

While a wide variety of methods for the formation of wood joints have been proposed, and.

wood joints of many different characters have been devised, such methods have proved cumbersome or ineii'lcient and such joints have been subject to a variety'of drawbacks including insufficiency of the union, tendencies toward breakage and deformation, unsightliness, expense of formation, etc. The result has been that although the formation of box ends by joining together small pieces of lumber is common practice, supplementary means such as inetal clips are ordinarily relied upon to hold the parts firmly together. Again in the formation of. composite flooring strips and in the union of pieces of wood for making furniture, doors, etc., various complicated structures and procedures have been necessary in order to secure a joint which is adapted for various of the uses to which such articles are put.

With the foregoing and other considerations in view, the invention contemplates the provision of a simple, firm, permanent and attractive wood joint which can be formed with extreme ease, of box ends utilizing such joints, and of simple and effective methods for the formation of such joints and of various articles-embodying the same.

Among the features of the invention are the use of a tongue-and-groove formation of a character such that the parts may be readily put together and securely held in place, the avoidance of uneven distribution of the glue, the application of glue only at thetongue-and-groove portion of the adjoining surfaces, the provision of means to prevent spreading of the sides of the groove and to relieve strain on tongue, and the provision of various combinations of elements and steps which result in a greatly improved product and a greatly simplified method of for-- mation.

One embodiment of the invention-in its various aspects is exemplified in the showing of Figs. 1 through 6. In Fig. 1 there is illustrated a blank adapted for the formation of box ends and comprising pieces of scrap lumber III, II, l2 and I3 which have been joinedtogether in accordance with the invention. As exemplified, the piece III has been formed with a pair of grooves l4-l4 along one of its narrow side surfaces andeach of the pieces ll, VIZ and I3 have been formed with tongues l5-l5 on oneof the narrow end sur-' faces of each. As will be observed, the width of each groove l4 increases outwardly,--at a 20 angle in the present instance,and the'width of each tongue correspondingly decreases outwardly, so that the tongues maybe moved into the grooves with the utmost ease, and so that glue applied to one or the other of these interfltting portions will not be scraped off as the two are, pressed together. As will also be apparent from Figs. 3, 4, and 5, the surface of the grooved piece 5 recedes, as shown at it, at each side of the groove and the surface of each tongue-carrying piece protrudes, as shown at H, correspondingly at each side of the tongue. Thus, spreading of the sides of the groove is prevented, and at the same time the strain on the tongue which normally results from lateral stresses is considerably relieved, since bending stresses will give an equalized strain throughout the joint. While in the preferred construction the walls of the-groove meet the receding surfaces IS in an acute angle; it will be understood that in various instances the receding and protruding surfaces, if utilized, may be spaced from the groove and tongue respectively, and also that they may, if desired, terminate short of the face of the board or the'proposed saw-line. Firm interlocking of the parts, and relief of strain is thus given by an exceedingly simple means which requires no additional wastage of wood and no especially complicated sawing operations. In this connection it is to be noted that the angularity of the walls of the tongue and groove should not be large, as increasing angularity will result in decreased wedging action and consequently in less mechanical strength in the joint and insuflicient tendency to hold the pieces together during the setting of the glue. In the formation of the joint, glue may be applied to either the tongue or the groove, but is preferably applied in the groove as indicated at l8 (Fig. 4) and the pieces pressed together. As above pointed out, the glue will not be scraped off the side walls of the groove, or of the tongue if applied thereto, during this movement. No glue is applied to the portion beyond the groove so that the presence of glue adjacent to the faces of the pieces joined where it will be unsightly, or to a point between pairs of tongues and grooves where the double-end blank is to be re-sawn, will be avoided. Since many glues have a dulling effect on saws, this feature is particularly advantageous in making the box ends and other procedures wherein re-sawing of the pieces is contemplated. It will be apparent that the provision of a jointsuch as exemplified, not only results in the formation of a particularly strong final structure, but also permits the bonding time to be reduced and the article to be handled much earlier than would otherwise be the case.

In the formation of a box end from a doubleend blank such as shown in Fig. 1, it is only necessary to saw the double-end blank throughout its extent on a plane as indicated by the dotand-dash line 20, there being produced two box ends, one of which is illustrated in Fig. 2. As will be apparent, a box end may be formed directly by joining relatively narrow pieces of lumber; and three, four or more box ends may be sawed from a single blank depending upon the thickness of 5 the stock used and the thinness of the box ends desired, it being only necessary to provide interfitting portions for each of the box ends'to be sawed from the multiple-end blank; If desired, each box end or other final article may embody a plurality of interfitting portions on each end glued, but ordinarily this is an unnecessary compllcation of the structure and of the procedure. In the formation of box ends or other articles, pieces of scrap lumber may be joined in any de- 75 sired manner depending upon the size of the 'larly strong and attractive product is pieces and the structure to be formed. For instance, the group of pieces ll, l2 and Il may be replaced by one, two, four, or any other desired number of pieces, the portion l0 may be replaced by a plurality of pieces and the portions may be variously arranged as may be necessary or desirable to fit them in properly. Ordinarily when a. single piece extending across the blank, such as the piece 10, is utilized, it is unnecessary to provide any special joint between the other pieces, such as H, Hand l3, although glue would be applied between their flat surfaces in most in- However, in instances where a particudesired, a joint such as contemplated by the invention may be provided between the piece I2 for instance and the pieces II and I3. Desirably the grain of the wood may extend along the pieces as indicated in the drawing, so that the grain of the various joined pieces runs in different directions, but that nevertheless all the tongues run in the direction of the grain. In a construction such as exemplified the provision of the protruding surfaces ll in the end grain assists in overcoming the tendency of the side grain at the exterior of the grooved pieces to curl up. If tongues are formed to join the piece l2 to the pieces II and IS, the tongues stances.

' should be formed on the piece I2 for the same reason and the pieces I l and I3 should be grooved, the tongues being formed in end grain in all cases, as will be apparent from Fig. 1.

As will be apparent a joint such as contemplated by the invention may be utilized in uniting a wide variety of types of construction. For example flooring boards may readily be formed of random short lengths as indicated at 2| and 22 (Fig. 6) The otherwise waste pieces may be matched and glued in the factory to make lengths convenient for laying. Tongue and groove flooring may also be end matched by the provision of a similar joint with or without gluing. Again, furniture framework may the-pieces in accordance with the invention in the manner indicated forexample in Fig. 'l where the piece 23 is grooved and the tongued piece 24 fitted against it, or doors having joints formed as above indicated may be constructed in a manner such for example as shown in Fig. 8, wherein the pieces 25 and 26 are grooved and cut away to receive tongued pieces such as shown at 21, 28 and 29, and the panels 30.

As will be apparent, in allthe structures exemplified, there are utilized joints such as exemplified in Fig. 3 and embodying the various features of the invention, but the utilization of constructions embodying only one or more of features disclosed have many advantages i'or a variety of purposes. However, in the preferred and exemplified forms each joint includes a wedge-shaped tongue I5 cut in end grain, as illustrated, and glued in the wedge-shaped groove 14 and unglued receding portions l8 and protruding portions II.

It will be appreciated that some glue may work out beyond the edges of the groove; and that while the term unglued is utilized for the sake of facility of expression to define certain of the surfaces, it is to be understood that this term'is used as referring to surfaces which do not carry any material amount of glue, at least at such portions thereof where glue is undesirable.

Since certain changes in carrying out the above method, and certain modifications in the articlewhich embody the invention may be made without be formed by gluinggroove and the unglued surfaces.

departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

The invention claimed is: I

1. A wood joint comprising juxtaposed pieces of wood having glued closely-interfltting portions of tongue and groove formation, unglued surfaces disposed laterally of said tongue and groove and extending to the edges of the pieces, and sharp bends between the tongue and the 2. A wood joint comprising juxtaposed pieces of wood, one having a tongue and the other a groove, said tongue and groove being glued together and said pieces having unglued surfaces disposed laterally of said tongue and groove and extending to the edges of the pieces, and sharp bends between the tongue and the groove and the unglued surfaces, said tongue and groove being of wedge-shaped formation, and a surface of the grooved piece receding at each side of the groove and a surface of the tongue-carrying piece protruding at each side of the tongue.

3.-A box-end or the like, comprising a piece of wood one edge-surface or which forms an edgesurface of the article, and a plurality of other pieces of wood at least certain of which have an edge-surface meeting the' opposite edge-surface oi the first-mentioned piece, the meeting edgesurfaces of said first piece and said certain of said pieces comprising a wedge-shaped tongue glued into a wedge-shaped groove and unglued surface portions disposed laterally of said tongue and groove and extending to the edges of the pieces, there being sharp bends in the meetin surfaces between saidtongue and groove and said unglued surface portions, and said unglued surface portions being inclined laterally of said bends to protrude in the direction of said tongue and to recede in the direction of said groove.

4. The method of forming box-ends and the like which'eomprises forming the edge surfaces of each of a plurality of pieces of wood to provide a plurality of spaced sets of closely interfitting portions adapted for wedging inter-em 

